I am seeking people's experience with drug budgets as part of
primary health care programs. We would be grateful for any
contributions.

A WHO figure says that one should expect a patient consultation rate
of 0.6 consults per year per person, and that adequate health care
should cost a government about $10 /capita.

A lot of information on the predominant diseases in an area would be
needed, but any estimates or experiences for budgeting essential
drugs on a per capita basis regardless of disease patterns or in
places where the disease patterns are known would be really helpful.